Electric ignition plug



Nov. 10, 1936. H. .1. LlNSE ELECTR IC IGNITION PLUG Filed July 23, 1932INVENTOB filmy Zlmsc BY [1 0 ATTORNE Patented Nov. 10, 1936 UNITEDSTATES PATENT OFFICE 5 Claims.

This invention relates to electric ignition plugs for use in internalcombustion engines for igniting the fuel charge in the engine cylinderembodying a shell whereby it is mounted in an opening in the enginecylinder and constitutes one of the plug electrodes, and a secondelectrode carried by an insulator body of translucent mate-rial, such asglass, with a portion projecting from the shell arranged with aprismatic surface whereby the light rays of combustion of the fuel aredeflected longitudinally through the insulator body and laterally ofsaid projecting portion whereby the burning of the fuel within theengine cylinder may be readily ascertained by observing said projectingportion of the insulator body, as shown in Letters Patent No. 1,846,741granted to me February 23, 1982.

In the arrangement of ignition plug shown in said Letters Patent theinsulator body does not extend for the entire length of the centerelectrode with the result that an unsupported portion of the electrodeextends from the body. To compensate for expansion and contraction ofthe parts the electrode carrying bore in the insulator body is ofgreater diameter than the electrode, the electrode being secured in thebore of the insulator body by an enlargement on the electrode engagingthe inner end of the insulator body and a nut threaded onto the outerend. To support said extended end of the electrode to prevent distortingof the electrode and thereby a varying in the spark gap a conical memberof translucent material was secured in abutting relation to the end ofthe insulator body and the materials of said conical member-andinsulator body having the same co-efficient of expansion, and theelectrode loosely extended through a bore into said member. While saidarrangement is satisfactory under ordinary fuel compression pressuresand heat in the engine cylinder, in the use of such arrangement withhigh fuel compression pressures, and consequent higher temperatures,such pressures and high temperatures and the expansion of the materialof the conical member tend to move the center electrode laterally andthis is augmented by the loose engagement of the electrode in theinsulator body and supporting member and thus vary the sparking gap bymoving the sparking terminal of the center electrode either too close ortoo far away from the sparking terminal of the shell electrode.

It is the object of the present invention to overcome said disadvantageby providing an improved construction and arrangement of mounting of thecenter electrode in the insulator body, and to an improved constructionand arrangement of supporting member for the end portion of theelectrode unsupported by the insulator body, and to provide means forthis purpose which is novel, cheap in structure and efiicient in use.

In the drawing accompanying and forming a part of this applicationFigure 1 is a side elevation of an ignition plug, partly in section,with the present invention embodied therein.

Figure 2 is a longitudinal sectional view of the ignition plug.

Figure 3 is a side elevation, on an enlarged scale, of a centerelectrode embodied in the present invention.

Figure 4 is a perspective view of the insulator body; and

Figure 5 is a perspective view, partly in section, of the support.

In carrying out the invention there is provided a shell electrode 1 ofthe usual structure having a skirt portion arranged with external screwthreads 8 for engaging the ignition plug in an opening in the cylinderof an internal combustion engine, and. an internal annular shoulder 9above the skirt portion to form a seat for an annular enlargement I0intermediate the ends of a section II of a composite insulator core orbody to sup port the same within the shell electrode I, and is securedtherein by a collar or sleeve 12 engaged within and having threadedconnection with the shell electrode with a sealing gasket l3 interposedbetween the upper portion of the insulator enlargement l0 and saidcollar, a gasket l3 also being interposed between the lower portion ofthe enlargement and shoulder 9 to seal the insulator body in the shellto prevent loss of compression in the engine cylinder.

The insulator body I! is of such a size relative to the shell electrodeto compensate for thermal expansion and contraction of the metal of theshell and collar, and consists of a transparent or translucent material,preferably glass, having a portion extended beyond the end of the shellelectrode that is engaged by the collar [2, arranged with a prismaticsurface 14 of suitable form to deflect and diverge the light rays ofcombustion transmitted longitudinally through the body laterallythereof, and shown as comprising a series of annular flutes. Tofacilitate the molding of the insulator body it is of a length so thatthe end opposite the end with the prismatic surface terminates at apoint within the threaded skirt 8 of the electrode shell and has a bore15 of uniform diameter leading from the end with the prismatic surfaceand terminating in an enlargement H5 at the opposite end, the side wallof which enlargement diverges or tapers slightly toward the end of theinsulator body.

The center electrode comprises a rod having two diameters and consistingof a body portion H which may be of uniform diameter and a sparkingterminal end portion l8 of reduced diameter. The body portion i1 isscrew threaded from the juncture of the body portion, with the reducedportion of the rod to a point intermediate the ends of the body portion,as at IS. The free end of the body portion of the rod is also screwthreaded and an annular abutment in the form of a collar or washer 20 isfixed in predetermined position thereon, in the present instance,intermediate the ends of said screw threads, as by swaging or otherwise,said washer being adapted to abut against the end of the insulator bodyto hold the rod electrode against movement in one direction relative tothe insulator body so that the body portion ll of the electrode willterminate within the bore enlargement IS with a portion of the threadedend positioned within the bore of the insulator body, as shown in Figure2, and thus providing the electrode within the bore of the insulatorbody with recessed portions and the reduced portion l8 to extend for apredetermined length beyond the skirted portion of shell 1. The threadedas well as the intermediate portion of the body of the electrode is ofless diameter than the bore in the insulator body, and the electrode ispressure sealed centrally therein by a suitable cementitious material,as at 2!, the embedding of the cement in the threads at both ends of theelectrode body I! serving to hold the electrode against longitudinaldisplacement and compensate for irregularities in the bore wall, as wellas rotary movement, as when screwing a conductor binding nut 22 onto thethreaded end of the electrode extended beyond the insulator body to bindan electric conductor between the nut and the abutment washer 2|].

The reduced electrode end i8 extends beyond the threaded end 8 of theshell in spaced relation to a sparking terminal in the form of the usualangular pin 23 secured in the end of the shell, and is supported by theother section of the composite core or body comprising a sleeve 24 andthe material having a diiferent co-efiicient of expansion, preferablylower, than the material of the insulator body, in the present instanceconsisting of a non-translucent and refractory insulator material, suchas porcelain having an outer glazed surface. The outer wall of thesleeve tapers from intermediate the ends to the opposite ends, as at 25,2B, the end 25 being engaged in the enlargement iii of the bore in theinsulator body being of a length and substantially equal to the lengthof said bore enlargement but of slightly less diameter and secured andsupported therein by a cementitious material, as at 21. The bore throughthe sleeve is of slightly greater diameter than the reduced portion I8of the electrode and the inner end of the bore is arranged with anenlarged threaded portion 29 for threaded connection with theintermediate threaded portion I9 of the rod electrode to positivelyretain the porcelain sleeve united with the translucent body andco-operate with the rod abutment 20 to secure the electrode againstlongitudinal displacement. The sleeve terminates at a point within theend of the electrode and may be further secured thereto by acementitious material interposed between the electrode and sleeve, as at28. It will be observed that the greatest outer diameter of theelectrode supporting sleeve is less than the end wall of the insulatorbody extending about the sleeve and thus providing a surface for thelight rays of combustion to be transmitted longitudinally through theinsulator body, and the glazing of the outer surface of the projectingportion of the sleeve serves to reflect and deflect the light rays ofcombustion to said end wall of the insulator body. The cementitiouslayer 2i interposed between the insulator body and the body portion llof the rod electrode also serves as a reflecting surface and facilitatesthe deflecting of the light rays laterally from the insulator body.

Having thus described my invention I claim:

1. In an electric ignition plug, an insulator body of translucentmaterial having a bore leading therethrough from one end and terminatingin an enlargement at the opposite end and having a prismatic exteriorsurface adjacent one end, a sleeve of non-translucent and insulatingmaterial seated at one end in the bore enlargement of the insulator bodyand having an outer diameter not greater than the diameter of said boreenlargement to expose the end of the insulator body, a cementitiousmaterial to secure the sleeve in the bore enlargement in the insulatorbody, an electrode having two diameters, the portion of less diameterextended through and of less di ameter than the sleeve bore toconstitute a sparking terminal, and the portion of, greater diameterextended through and of less diameter than the bore in the insulatorbody and having recesses therein within said bore and a threadedconnection with the sleeve, and cementitious material interposed betweenthe electrode and walls of the sleeve and insulator body in embeddingrelation to the recesses in the electrode to pressure seal the electrodein the insulator body and sleeve.

2. In an electric ignition plug, an insulator body of translucentmaterial having an exterior prismatic surface at one end and a bore 01uniform diameter leading therethrough from one end and terminating in anenlargement at the opposite end of the body with the side wall of theenlargement diverging toward the end of the body, a porcelain sleevehaving an outer glazed surface and tapering from intermediate the endsto the opposite ends, said sleeve engaged at one end in and the taperof. the outer wall conforming to the taper of the bore enlargement ofthe insulator body and the sleeve bore being 01 less diameter than andextending coaxially of the bore in the insulator body, and the greatestouter diameter of said sleeve being less than that of the boreenlargement to expose the end wall of the insulator body about thesleeve for the transmitting of light rays longitudinally through thetranslucent body to be deflected laterally by the prismatic surface, thebore of the sleeve at the end engaged in the bore enlargement of theinsulator body being arranged with a screw-threaded enlargement, a rodelectrode having two diameters extended through and of. less diameterthan, the diameters of the bores in the insulator body and sleeve withthe portion of less diameter engaging the bore of the porcelain sleeveand the portion of larger diameter engaging the bore in the insulatorbody, said portion of larger diameter being screw threaded at both endsfor an extent so that a portion of the screw threads is positionedwithin the bore of the insulator body with the threads adjacent theportion of lean diameter engaging the threads or the bore enlargement ofthe sleeve to secure the sleeve within the insulator body enlargementand on the electrode and hold the electrode against longitudinaldisplacement in one direction, and a cementitious material interposedbetween the electrode and the walls of the bores in the insulator bodyand sleeve and in embedding relation to the screw threads of. theelectrode within the bore of the insulator body to pressure seal theelectrode therein.

3. In an electric ignition plug, a composite insulator body embodyingendwise secured sections having alined bores therethrough, one sectionconsisting of a translucent material and the other section of anon-translucent refractory material of less cross section than the firstsection to expose the wall of the first section extending about thesecond section, and a rod electrode extended through and secured in thebores of and connecting the sections of the insulator body.

4. In an electric ignition plug, a composite insulator core consistingof a body of translucent material having an exterior prismatic surfaceat one end and a bore therethrough having an enlargement at the endopposite to the end with the prismatic surface and a sleeve of.non-transparent refractory material seated in the bore enlargement ofthe body and of less diameter than the body to expose the end wall ofthe body about the sleeve and said sleeve having a bore therethrougharranged with a screw threaded enlargement in the end engaged in thebore enlargement of the insulator body, a rod electrode extended throughthe bores of the body and sleeve having screw threaded portions at oneend and intermediate the ends, and having an abutment fixed thereonintermediate the threaded end portion to engage the end of thetranslucent body and the intermediate screw threaded portion adapted tohave connection with the screw threaded enlargement of the sleeve toconnect the sleeve to the translucent body and in connection with theabutment securing the electrode against displacement in the insulatorcore, and a cementitious material between the electrode and walls of thebores in the insulator body and sleeve in embedding relation to thescrew threads of the electrode to pressure seal the electrode in theinsulator body and sleeve.

5. In an ignition plug for internal combustion engines, the combinationof a shell having an interior annular shoulder intermediate the ends andan externally threaded end portion for mounting in an opening in theengine cylinder, a body of translucent insulator material engaged in theshell having an annular enlargement for seating against the shoulder inthe shell, said body having an end portion projecting from the shellarranged with an exterior prismatic surface and a bore through the body,a collar encircling the body and having threaded connection with theshell to engage the annular enlargement of the body and secure it to theseat in the shell, a sleeve of non-transparent and refractory materialengaged in the end of the body within the exteriorly threaded portion ofthe shell and of less diameter than the body to expose the end wallportion of the body about the sleeve within the shell to transmit thelight rays of, combustion in the engine cylinder through the body to theprismatic surface and by the latter deflected laterally, and a rodelectrode extended through the bores of the body and sleeve, said rodhaving an abutment fixed adjacent one end to abut the outer end of thetranslucent body and arranged to connect the sleeve to the translucentbody and thereby in conjunction with the abutment held againstlongitudinal displacement relative to the translucent body and sleeve.

HARRY J. LINSE.

